DASH04 project description

DASH04

Summary

In an effort to build the last large (4m) solar (viewing the sun; obviously during the day) telescope. This telescope will have about 1000 actuators to dynamically adjust for atmospheric interference, but they have limitations, so it is necessary to site this scope where atmospheric turbulence (characterized by the refraction structure parameter, C_n^2) is minimal.

Data have been taken at 6 candidate sites over the past 2 years using two types of scintillometers, but are highly sensitive to corrections used in the near-field of view of these instruments. The magnitude of these corrections is enough to change a site from being determined to be usable to unusable or vice versa.

Thus, a verification data set is needed to determine if any of these correction schemes produce values which are good enough for site evaluation. In situ measurements (either from a tower or balloon) of C_n^2 (from C_T^2 and C_q^2) should produce unambiguous results. Sodar measurements of C_n^2 also may provide adequate measurements.